Tests

Provide a better fallback value for the python_version option #15952

Job	Run time
Test mypyc suite with 32-bit Python	8m 23s
Test suite with py39-ubuntu, mypyc-compiled	14m 37s
Test suite with py39-windows-64	22m 22s
Test suite with py310-ubuntu	11m 49s
Test suite with py311-ubuntu	8m 24s
Test suite with py312-ubuntu, mypyc-compiled	13m 55s
Test suite with py313-ubuntu, mypyc-compiled	14m 12s
Test suite with py314-dev-ubuntu	17m 27s
mypyc runtime tests with py39-macos	4m 35s
Type check our own code (py39-ubuntu)	2m 2s
Type check our own code (py39-windows-64)	2m 24s
Formatting and code style with Black + ruff	1m 59s
	2h 2m 9s

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